Valve actuator means

ABSTRACT

Improved fluid-operated valve actuator means for rotating a valve shaft in opposite directions through a given angle (preferably, 90* in the case of a quarter-turn valve). The invention is characterized by the provision of cam means connected with the output shaft and arranged in a chamber between a pair of freely movable operating pistons. When one end of the chamber is pressurized, the corresponding piston applies an operating force to the cam to rotate the cam and the output shaft through the given angle. In one embodiment, reversing valve means are provided for reversing the ends of the chamber that are pressurized and vented, respectively. In a second embodiment, one end of the chamber is alternately pressurized and vented, respectively, to achieve the desired rotation of the output shaft, the other end of the piston being enlarged to define a pressure fluid reservoir operable to return the output shaft to its initial position. In a third embodiment, spring means assist in returning the output shaft to its initial position.

[451 Nov. 7, 1972 [54] VALVE ACTUATOR MEANS [72] Inventor:

[73] Assignees: Societe Argenton; Societe Anonyme,

Luxemburg, Luxembourg [22] Filed: April 27, 1970 [21] Appl. No.: 32,121

Jean Viaud, Paris, France [30] Foreign Application Priority Data April28, 1969 France ..6913427 [52] US. Cl ..92/73, 91/399 [51] Int. Cl..F01b 1/02 [58] Field of Search ......92/73, 68, 138

[56] References Cited UNITED STATES PATENTS 3,614,913 10/1971 Clark..92/138 1,774,087 8/1930 Dunn ..92/73 2,614,540 10/1952 Morton ..92/73FOREIGN PATENTS OR APPLICATIONS 602,982 3/1960 ltaly ..92/73 PrimaryExaminer-Paul E. Maslousky Attorney-Lawrence E. Laubscher [57] ABSTRACTImproved fluid-operated valve actuator means for rotating a valve shaftin opposite directions through a given angle (preferably, 90 in the caseof a quartertum valve). The invention is characterized by the provisionof cam means connected with the output shaft and arranged in a chamberbetween a pair of freely movable operating pistons. When'one end of thechamber is pressurized, the corresponding piston applies an operatingforce to the cam to rotate the cam and the output shaft through thegiven angle. In one embodiment, reversing valve means are provided forreversing the ends of the chamber that are pressurized and vented,respectively. In a second embodiment, one end of the chamber isalternately pressurized and vented, respectively, to achieve the desiredrotation of the output shaft, the other end of the piston being enlargedto define a pressure fluid reservoir operable to return the output shaftto its initial position. In a third embodiment, spring means assist inreturning the output shaft to its initial position.

1 Claim, 4 Drawing Figures PME'N'TEDnnv 11912 3,702,091

SHEET 1 OF 3 TQM V1 mu! INVENTOR.

v A'TTDWY VALVE ACTUATOR MEANS This invention relates generally toautomatic actuator means for quarter-turn valves, and more particu larlyto valves which are operated by rotating the axis of the valve by aquarter turn, said actuator means being of the pressure fluid (gas orliquid) type.

Valve actuator means controlled by a fluid under pressure are known inthe prior art, said actuator means including one or more pistonsoperable in a cylinder as controlled by a solenoid-operated controlvalve. However, most of these known devices are rather cumbersome.Generally, the rod of the piston (or pistons) is linked bilaterally withthe axis of the valve, and therefore the apparatus must have largedimensions so as to be able to perform the maximum effort correspondingwith the starting phase. The known actuator systems are furthercomplicated in that there are no means for correction of the resistanttorque of the valve, and such a correction system does not accuratelyconform to the variations of the resisting torque.

The primary object of the present invention is to provide a smallactuator, using an arrangement permitting its adaption to all theresisting torques encountered during operation. The actuator means canfurthermore be used on various types of valves by simply changing onemember (specifically, a cam member) to which the force bringing aboutthe rotation of the valve is applied.

A more specific object of the invention is to provide valve actuatormeans including, in a cylinder, a pair of free pistons that engage, bydirect unilateral contact, a cam between the two of them, said cam beingmounted on the valve control shaft in an eccentric fashion with respectto said shaft, so as to bring about the rotation of this shaft in onedirection or the other when the pressurized fluid is introduced at oneor the other extremity of the cylinder.

A further object of the invention is to provide valve actuator meansincluding one or more of the following features:

a. A supplementary pressure (pneumatic or liquid) fluid reservoir isprovided in one of the ends of the cylinder, and a small-diameterconduit alternately connects this end of the cylinder to the other endand to atmosphere, respectively, with the help of a pressureresponsivevalve means so as to make it possible very progressively to establishsufficient return pressure on the end of the reservoir in order toobtain a single-action actuator;

b. A spring is introduced between one of the ends of the cylinder andthe corresponding piston so as to provide a single-action actuator;

c. The profile of the cam corresponds to the variable effort which thevalve requires for its operation depending upon the different positionsof the valve member relative to its seat; and

d. The cam is provided with a very hard metal belt and the surface ofeach piston in contact with the cam is provided with an addedself-lubricating portion consisting of hard substance.

Other objects and advantages of the invention will become apparent froma study of the following specification, along with several forrns ofimplementation, given here simply by way of example, without anylimitations, and represented schematically in the attached drawingswhere:

FIG. 1 is an axial cross-section view of a valve actuator according tothe present invention;

FIGS. 2 and 3 are axial cross-sectional views of two additionalembodiments of the invention; and

FIG. 4 is a schematic view of the cam means used in a valve actuatoraccording to the invention.

The valve actuator according to FIG. 1 essentially involves acylindrical housing 1 in which are mounted two free pistons 2 and 3.Between these pistons there is arranged a cam member 4 which, forsimplicity, is illustrated as having a circular configuration. The camis secured to the control shaft 5 of a valve member (not shown). Thecenter of the cam is eccentric with respect to the valve control shaft.The housing includes openings 6 and 7 which alternately conduct thepressure fluid through ducts 8 and 9 to the extremities of the chamberof housing 1 in accordance with the position of the solenoid-operatedreversing valve means.

The two pistons 2 and 3 are freely supported in the cylinderv forlongitudinal and rotational movement. Since there are no guide means,the periphery of each piston presents a rather large surface consistingof two annular flange portions 10 between which is provided a groove 11for receiving packing means (not shown).

In operation, the cam 4 which operates the valve shaft rolls with acertain friction on the opposed surfaces 12, 12 of the pistons. In orderto prevent wear and tear, the pistons are provided with aself-lubricating substance or they may have, on surfaces 12, an addeddisk consisting of hard self-lubricating substance, or a roller may bemounted in the center of the surfaces 12 to reduce the frictioncoefficient and to increase the yield.

The operation of the apparatus is very simple. The orifices 6 and 7 areconnected in a known manner with the pressure source and sump (or vent),respectively, via conventional-solenoid reversing valve means. As thepressure fluid is supplied via orifice 6, the outside air is driven outthrough orifice 7. During the displacement in the direction of arrow F,for example, piston 2 pushes cam 4 which is forced to turn as a resultof the eccentric position of its pivoting axis and the shaft 5 of thevalve is consequently rotated. The operation of the solenoid reversingvalve causes the shaft of valve 5 to turn in the opposite direction.

It is apparent that when the actuator is not under the influence of themoving fluid, the two pistons are entirely'free since they are notconnected to the cam by a small rod, a rack, or any other connection, orto each other. One important consequence of this is that the actuator isautomatically disconnected when it is no longer under the influence ofthe moving fluid, thus permitting very easy manual operation of thevalve shaft (for emergency purposes, for example). In effect, theautomatic actuator according to the invention can, in the known manner,present a shaft output end on the other side of the valve with respectto the cylinder so as to permit manual control of the valve in case theactuator does not function. While, for simplicity, the mechanicalindicator of the position of the valve, as well as the possiblecontactors for the remote indication or remote registration of theposition of the valve,

have not been illustrated, it should be mentioned that one of theadvantages of this actuator is that it permits placement of the elementsinside the actuator while keeping its size small.

According to the modification of the invention shown in FIG. 2, theactuator is designed to function in a single acting way when only one ofthe pistons is in direct contact with the source of pressure fluid. Thisarrangement is particularly advantageous when the valve, controlled bythe actuator, does not require a holding torque to maintain the valve inthe open or closed position. The housing .1 has been noticeably extendedon one side to define a reservoir 13' on this side of the cylinder whichis larger than the chamber 14' on the other side, when the pistons are,respectively, in the two extreme positions. Furthermore, asmall-diameter conduit 15' connects reservoir 13 to chamber 14' througha pressure-responsive retaining valve consisting of a ball 16' whichnormally closes a small opening 17' communicating with chamber 14'.

Ball. 16', in its other extreme position, closes off a seat 18' made ona drill hole 19' leading to atmosphere. The ball thus' causes chamber13' to be alternately connected with atmosphere and with chamber 14',respectively.

As we can see, the purpose of this arrangement is to avoid giving theactuator large dimensions. In effect, if

we use a spring or an additional compressed-air reservoir, it may beaccomplished that, during the first stroke, it is necessary to use forcenot only to operate the valve but also to compress the spring or thereturn fluid. Furthermore, when a compressed'fluid is used for thereturn, the stored pressure energy must be sufficiently large that therewill not be too great a pressure drop at the end of the return stroke.

The device operates as follows. Assume that the pistons are in theextreme right-hand position compressed air is introduced through inlet20. The entire assembly then moves to the left, and since thecylindrical elements close the opening 17, the air which is in chamber13' is driven out through conduit and escapes into the atmospherethrough opening 19'. At the end of the stroke, the opening 17' isuncovered. The ball is projected toward its upper seat 18', and space13' is filled progressively with compressed air in a relatively slowmanner through conduit 15 which has a small diameter. In this way thefluid introduced at chamber l3'practically does not offer any resistanceto the stroke of the pistons at the end of the operation.

At this moment, the controlled valve is completely opened or closed andthe compressed air continues to arrive through inlet going to chamber14', and it continuesto move toward chamber 13' through conduit 15'until the pressure is the same in chambers 13' and 14'. At this moment,the assembly is in balance under pressure and the valve is immobilizedin its extreme position.

If the influx of, air through inlet 20 is terminated and inlet 20'. isplaced in communication with the atmosphere, the compressed airaccumulated in chamber 13 pushes the mobile device toward the right upto the other extreme position. Of course, a little bit of compressed airescapes through conduit 15' but this is of no importance to theoperation because this conduit has a small diameter, calculated in sucha manner that its flow speed will be small with respect to the speed ofthe piston.

On the other hand,.since chamber 13' is much larger than chamber 14',the compressed air accumulated in chamber 13 hasa' volume sufficient tocause the device to perform the return stroke without a very noticeablepressure drop. After the end of this opera-- tion, the two chambers 13'and 14 are at atmospheric pressure and we once again have equilibrium.It must be noted that, in certain cases involving quarter-turn valves,which are rather rare, by the way, it is necessary to exert aneffortwhenthe two chambers are in communication with the atmosphere inorder to keep the valve in position. Inthis case, it is easy to providea spring on one side, exerting just the right complementary actionnecessary to keep the device butting against the other side of thecylinder. When the valve is in the other position, .the pistons may beprovided with different diameters so as to obtain a differential effectwhen the two chambers 13' and 14 are under pressure; this. differentialeffect here applies the mobile assembly against a stop. Naturally, inthe, case of the simple action, one can use a spring to bring about thereturn stroke.

FIG. 3 is a schematic illustration of such a version. For this purpose,cylinder 1" has been enlarged, as in the earlier case, so as toconstitute sufficient space at 13" for one or more springs ,21", spring21" being supported in a recess 22" contained in the piston 2", forexample.In this case, there is only one pressure fluid inlet 20", withthe fluid here working on piston 3".

The operation is alsovery simple in this case and the nozzle isconnected alternately to the pressure source and to the air,respectively, with the help of a solenoidoperated control valve. Thus,when piston 3" has been moved toward the left due to the action of thefluid, as indicated in FIG. 3, spring 21" has been compressed. At thatmoment, it suffices to place inlet 20" in contact with atmosphere inorder to have spring 21" expand, pushing the entire assembly toward theright, which causes the cam 4", and, consequently, valve shaft 5" toturn. While only one spring has been illustrated, it is obvious thatseveral springs could be used, if desired.

In the schematic illustrations of FIGS. 1-3, the cam has beenillustrated as having a circular configuration. In fact, it ispreferable to have a cam with a profile corresponding to the variableeffort required by the valve or its operation.

The profile of the cam can be calculated in a practically exact manner.In effect, for a constant air pressure, the force exerted on the cam isconstant in terms of force and direction. The variation of the rotationtorque is a function only of the point where the cam rubs on the movingpiston. It thus suffices to say that the moving torque, which is afunction of the position of the contact point of the cam is equal to theresisting torque of the valve which in turn is a function of its angleor rotation. Furthermore, it is also easy empirically to determine thebest profile for the cam by successive approximations.

FIG. 4 shows such a cam, said cam being formed of light metal andincluding a belt in the form a plate spring 23 whose two extremities24are clamped on a cavity 25 contained in the cam. The dot-dash lineillustrates the zones of contact 26 of the cam with the pistons.

Of course, the versions-described above and shown in the attacheddrawings are given here only by way of simple examples without anyrestrictions, and it is apparent that one could modify the shape,arrangement,

nature, and mounting of its elements in any suitable fashion withoutdeviating from the inventive concepts.

' What is claimed is:

1. Valve actuator means for rotating a valve operating shaft alternatelyin opposite directions through a given angle of less than 180,respectively, comprising a. piston and cylinder means including (1) ahousing (1) containing a longitudinally extending cylindrical chamber,said housing including side and end walls; and (2) a pair of spacedpistons (2, 3) mounted for independent free reciprocatory movementlongitudinally of said chamber, respectively;

b. a cam member (4) arranged in said chamber between said pistons, saidcam member being contained in a plane colinear with the longitudinalaxis of said chamber and having a non-circular cam profile designed toeffect a desired non-uniform operation of the pistons, the profilesurface of said cam member including a layer of hard metal (23);

. a valve operating shaft (5) journalled in said housing side wall andextending at one end within said chamber, said shaft being normal tosaid longitudinal plane and laterally offset from the longitudinal axisof said cylindrical chamber, said cam member being eccentricallyarranged relative to and rigidly connected with said valve operatingshaft; and

. means for supplying pressure fluid to a first end of said chamberbetween a first one of said pistons and the corresponding end wall toforce said first piston into operating engagement with the surface ofsaid cam member and thereby rotate said cam member in one directionthrough said given angle.

1. Valve actuator means for rotating a valve operating shaft alternatelyin opposite directions through a given angle of less than 180*,respectively, comprising a. piston and cylinder means including (1) ahousing (1) containing a longitudinally extending cylindrical chamber,said housing including side and end walls; and (2) a pair of spacedpistons (2, 3) mounted for independent free reciprocatory movementlongitudinally of said chamber, respectively; b. a cam member (4)arrangEd in said chamber between said pistons, said cam member beingcontained in a plane colinear with the longitudinal axis of said chamberand having a noncircular cam profile designed to effect a desirednon-uniform operation of the pistons, the profile surface of said cammember including a layer of hard metal (23); c. a valve operating shaft(5) journalled in said housing side wall and extending at one end withinsaid chamber, said shaft being normal to said longitudinal plane andlaterally offset from the longitudinal axis of said cylindrical chamber,said cam member being eccentrically arranged relative to and rigidlyconnected with said valve operating shaft; and d. means for supplyingpressure fluid to a first end of said chamber between a first one ofsaid pistons and the corresponding end wall to force said first pistoninto operating engagement with the surface of said cam member andthereby rotate said cam member in one direction through said givenangle.